The role of enteral nutritional supplements in the prevention and treatment of protein calorie malnutrition in cancer is not established. This study will examine the efficacy of enteral nutritional supplementation in preventing or reducing the progression of protein-calorie malnutrition in lung cancer patients utilizing a randomized prospective clinical design, a control population, and a single pre-selected treatment regimen. Patients with unresectable bronchogenic carcinoma with chronic lung disease prior to the development of severe protein-calorie malnutrition, based on weight status, performance status, and clinical characterstics, will be randomly assigned to control group A and enteral supplemented (group B) groups. Two groups of patients with chronic lung disease and no evidence of cancer will be matched carefully to each cancer patient and serve as controls in supplemented (group D) and control (group C) groups. Patients from all groups will be studied under metabolic ward conditions to determine basal energy expenditure, hormonal status, and multiple aspects of carbohydrate and protein metabolism. Estimated protein and calorie requirements will be supplied via carefully designed standard diets to all groups. Group B and D from the cancer control populations will receive outpatient enteral supplementation designed to provide a 25% caloric supplement above basal requirements. Patients from all groups will be studied under metabolic ward conditions every two months and biweekly as outpatients. The effects of enteral supplementation on chemotherapeutic drug disposition and standard drug-related toxicity and response criteria will be examined. Outpatient and inpatient data will be compared. Based on a careful analysis of all the data, both the efficacy of this regimen of nutritional treatment will be examined and specific hormonal and metabolic aberrations will be examined which may define a pattern of nutritional disease, amenable to therapeutic intervention with specific hormonal, metabolic and nutritional therapies aimed at preventing, reversing, or treating the progression of protein-calorie malnutrition in patients with unresectable bronchogenic carcinoma.